A microfluidic flow control device includes a fluidic chamber, a first and a second microfluidic channel, at least one sealing surface between the first and the second channels, and a floating element disposed within the chamber. The floating element is capable of intermittently engaging the sealing surface, and movement of the floating element affects fluid flow between the first channel and the second channel. The floating element may be moved by fluid pressure, gravity, or an applied force such as a magnetic field. Multiple flow control regions may be integrated into a flow control system.